Hydraulic torque converter



March 24, 1964 R. c. SCHNEIDER 3,125,857

HYDRAULIC TORQUE CONVERTER Filed July 11, 1962 4 Sheets-Sheet 1 Me iMarch 24, 1964 R. c. SCHNEIDER 3,125,857

HYDRAULIC TORQUE CONVERTER Filed July 11, 19 62 4 Sheets-Sheet 2 In deain! faymond (-fcbfie a'der- March 24, 1964 7 Re. SCHNEIDER 3,125,857

HYDRAULIC TORQUE CONVERTER Filed July 11, 1962 4 Sheets-Sheet 3 msruvEncE 5610 Maui March 1964 R. c. SCHNEIDER HYDRAULIC TORQUE CONVERTER 4Sheets-Sheet 4 Filed July 11, 1962 United States Patent 3,125,857HYDRAULHC TGRQUE CGNVERTER Raymond C. Schneider, Rockford, Ill, assignorto Twin Disc Clutch Company, Racine, Wis., a corporation of WisconsinFiled July 11, 1962, der. No. 269,1397 6 Qlaims. (Cl. 6ll-54-) Myinvention relates to hydraulic torque converters of the single stagetype which are characterized by optimum performance and a type of designenabling economical manufacture.

Gne object of the invention is to provide an hydraulic torque converterin which the attainment of the desired performance is achieved byproperly coordinating a number of critical factors including a novelshape of the torus which is provided with continuously curving inner andouter walls, a minimum length of the torus in conjunction with anoutflow irnpeller, an inflow turbine and an optimum design of the statorwhose blades are very nearly symmetrical with the inner bend of thetorus, and a minimum length of the unbladed, outer bend of the torusbetween the outlet of the impeller and the inlet of the turbine.

A further object is to provide a converter of the character indicated inwhich the impeller, turbine and stator blades are simply curved betweentheir inlet and outlet tips and are not twisted therebetween whereby inthe making of the sand cores preparatory to separately casting theimpeller, turbine and stator in one piece, the master blades thereforare draftable and capable of easy removal from the sand core.

In the drawings:

FIG. 1 is a fragmentary, sectional elevation of the improved hydraulictorque converter.

FEGS. 2, 3 and 4 are elevations of the impeller, turbine and statorblades, partly in section and L1 each instance showing a few of theblades, looking in the direction of the arrows 2;, 3 and 4,respectively, in FIG. 1, the several core rings being omitted.

PEG. 5 is a diagrammatic view illustrating the construction fordetermining the shape of the torus and the blade positions.

FIGS' 6 and 7 show characteristic curves of the converter.

Referring to FIG. 1, the numeral 141 designates the rotating housing ofthe converter and includes an end wall 11 transverse to the axis of theconverter, an axially spaced, impeller wheel ring 12 and an annular wall13 connecting the wall 11 and ring 12. The end wall 11 is drivenlyconnected to a source of power (not shown) by a connector 14 to therebyprovide for rotation of the impeller wheel ring 12. The latter formspart of an outflow impeller 15 which otherwise includes a core ring 16axially spaced from the wheel ring 12 and a plurality of impeller blades17 equispaced around the wheel and core rings 12 and 16, respectively,and bridged therebetween. As subsequently noted in more detail, theimpeller 15, including the component parts above, is formed as a singlecasting.

The discharge from the impeller 15 enters one end of a reversely curved,unbladed, outer passage 13 whose opposite end connects with the inlet ofan inflow turbine 19 which includes a wheel ring 29, an axially spaced,core ring 21, and a plurality of turbine blades 22 equispaced around thewheel and core rings 21 and 21, respectively, and bridged therebetween.The turbine 19 is also formed as a single casting. The turbine wheelring 21) has splined connection with a load shaft 23, one end of whichmay be piloted in a bearing 24 carried by the Wall 11.

Ice

The discharge from the turbine 19 enters one end of a reversely curved,inner passage 25 whose opposite end connects with the inlet of theimpeller 15 and the latter passage is for the most part bladed by astator 26 comprising a wheel ring 27, a core ring 28 spaced therefrom,and a plurality of stator blades 2?! bridged between the wheel and corerings 27 and 28, respectively. The stator 26 is also formed as a singlecasting as will be presently described. The stator 26 may be permanentlyheld against rotation by appropriate connection to astationary sleeve30, or an overrunning clutch 31 may be interposed between the stator 26and sleeve 30, these alternatives being conventional.

As shown in FIG. 1, the impeller 15, passage 18, turbine 19, passage 25,and the stator 26 are related to form a closed, generally pear or eg-shaped, toroidal path for the working liquid except for an inletpassage 32 in the sleeve 3d and an annular passage 33 included betweenthe sleeve 31) and load shaft 23. The last named passages connect withthe toroidal circuit for conventional supply and discharge of coolingoil. Further, the impeller and turbine blades 17 and 22 are located inthe outward and inward flow parts, respectively, of the toroidalcircuit, while the stator blades 29 are positioned for nearly axial flowin the reversely curved, inner passage 25.

As shown in FIGS. 2, 3 and 4, the impeller, turbine and stator blades17, 22 and 29 are curved, but not twisted, between their inlet andoutlet tips 34 and 3,5, 36 and 37, and 38 and 39, all respectively.Further, referring to FIGS. 1 and 2, the impeller blades 17 are normallyrelated to the wheel and core rings 12 and 16, respectively, and thewheel ring end 411 of each impeller blade 17' has a greater linearlength than that of the core ring end 41 with suflicient foundryapproved draft between these ends to. enable the making of a sand coreby shell or common sand molding procedures preparatory to casting ashereinafter noted. The same conditions are true with respect to normalpositionings of the turbine and stator blades 22 and 23 relative totheir wheel and core rings 20 and 21, and 27 and 28, all respectively,and with respect to the like length differences of the wheel andcorering ends 42 and 43, respectively, of each turbine blade 22, and of thewheel and core ring ends 44 and 45, respectively, of each stator blade29. The draftable characteristics of the turbine and stator blades 22and 29, respectively, are similar to those of the impeller blades 17.

It has heretofore been stated that the toroidal path of the converter isegg or pear-shaped, but this is only a most general reference. Actually,for the performance required and the structural factors desired, theshape of the torus, designated generally by the numeral 4-6 in FIG. 5,is based upon a number of considerations which will now be discussed.

Denoting the outermost radius of the torus 46 from the converter axis 47by R, basic factors include a construction rectangle 48 whose shortsides 49 and 50 are parallel to and at radii of approximately .95R and.46R, respectively, from the converter axis 47 and whose long sides 51and 52 are normal to the converter axis 47 and have an approximatespacing of 36R. The rectangle 48 is in bounding relation to aconstruction and continuously curving, median design line 53 andindicated sides of the rectangle 48 are tangent to the line 53 inlocations presently established. The median design line 53 is partlydetermined by a number of design points A to J, inclusive, whose seriesrelation is, for convenience, in the direction opposite to the toroidalflow and whose coordinates in relation to the converter axis 47 as theX-axis and a construction base line 54 normal to the axis 47 andextending midway between the rectangle sides 51 and 52, the base line 54serving as the Y-axis, are as follows, positive and negative valueslying to the right and left, respectively, of the base line 54, asviewed in FIG.

The median design line 53 is further determined by a number of tangentspassing through the design points A to J, inclusive, and forming withthe converter axis 47 angles having the following approximate values, itbeing 'noted from FIG. 5 that the rectangle sides 49, 51, 50

and 52 respectively constitute the tangents passing through the designpoints A, C, F and I:

Design Points Tangents Angles,

degrees A" 49 0 B- 55 49 C 51 90 D 56 109 E- 57 152 F 50 180 G 58 218 Fr59 247 I. 52 270 .T 60 313 The design points and tangents listed abovehaving been located, the median design line 53 is drawn through suchpoints in tangential relation to the indicated tangents as an endlessline which is characterized by a continuously changing, smooth curvaturebetween each adjacent pair of design points.

The median design line 53 provides a basis for the sizing of the torus46 since it is employed as the locus of the centers of an infinitenumber of circles, one of which is identified by the numeral 61 in FIG.5, and wherein the diameter D of any circle is determined by thefollowing formula:

i 3%)1rR 21r distance of circle center from axis 47 V The quantity Rbeing the outer radius of the torus 46 as stated above.

With a sufficient number of circles 61, it will be apparent that, innerand outer, endless and continuously curving lines can be drawn to all ofthe circles 61 to define the inner and outer walls 62 and 63,respectively, of the torus 46. The diameters of the circles 61 varyinversely with the distances of their centers from the converter axis 47so that, as these distances decrease, the circle diameters increase. Thecross-sectional area of the torus 46 normal to the median design line 53between the inner and outer walls 62 and 63, respectively, anddisregarding the impeller, turbine and stator blades 17, 22 and 29,respectively, is substantially constant and is equal to approximately20% of the area of a circle R, the factor R being identified above.

The positionings of the inlet and outlet tips 34 and 35, 36 and 37, and38 and 39 of the impeller, turbine and stator blades 17, 22 and 29,respectively, are controlled by the following considerations. Withrespect to position, each of these tips includes a design point asdesignated above and, with respect to inclination relative to theconverter axis 47, each of these tips is considered to be a lineobtained by the intersection of the surface of a construction cone withthe cross section of the torus as viewed in FIG. 5. Angle values ofthese lines and hence of the blade tips as formed with the converteraxis 47 '4 are positive or negative depending upon whether the apex ofthe associated cone lies to the right or left, or on the impeller orturbine sides, respectively, of the base line 54 in FIG. 5.

For the impeller blades, the inlet and outlet tips 34 and 35 includedesign points D and B and form with the converter axis 47 angles of;-[-3423 and 2725', all respectively. For the turbine blades, the inletand outlet tips 36 and 37 include design points I and H and form withthe converter axis 47 angles of +2835' and 3453', all respectively. Forthe stator blades, the inlet and outlet tips 38 and 39 include designpoints G and E and form with the converter axis 47 angles of 65 7 and;+7638', all respectively.

From FIG. 5, it will be apparent that the torus 46 is bladed betweendesign points D and B to form the outflow impeller 15, is further bladedbetween design points I and H to form the inflow turbine 19, and isfurther bladed between design points G and E to form the nearly axialiiow stator 26 which may be either fixed in position or conventionallyarranged to float by means of the overrunning clutch 31. The portions ofthe torus between design points B and I, H and G, and E and D,respectively,

are unbladed.

A torus incorporating the above design is characterized by a number ofadvantages. Provision is made for minimum length of the torus inconjunction with an optimum design of a nearly axial fiow stator, aminimum, unbladed length of the torus between the outlet of the impeller15 and the inlet of the turbine 19, and a minimum of friction lossesunder operating conditions. The impeller v is a single casting includingthe wheel and core rings 12 of any of the blade angles of the finishedblades.

Considering the impeller 15, for example, the master blades are mountedon a first mold ring having a curved surface shaped identical with thewheel ring 12 portion of the torus surface 63 (see FIG. 5) and areabutted by p a second mold ring having a curved surface shaped identicalwith the core ring 16 portion of the torus surface 62. This assembly isthen placed in a core box to receive the molding sand, either by Way ofshell or common sand molding. When the sand has cured sufficiently, thefirst mold ring, corresponding in curvature to the impeller Wheel ring12, and the master blades are moved away from the sand core, thedraftability of the master blades permitting this movement. Consideringthe mold rings related in the manner of the impeller portions of thetorus surfaces 62 and 63, the movements of the mold ring forming theimpeller portion of the surface 63 and of the master blades would be ina direction away from an imaginary line corresponding to the base line54 and the movement of the mold ring forming the impeller portion of thesurface 62 would be in the opposite direction. The sand core thus formedis placed in the pattern and casting thereafter proceeds in the usualway. The same procedure is employed in the making of a sand core for theturbine 19.

Due to the positions of the stator blades 29, the pro cedure for makingthe stator sand core is somewhat different. As in the making of theimpeller and turbine sand cores, mold rings for determining thecurvatures of the stator wheel ring 27 and core ring 28 portions of thetorus surfaces 63 and 62, respectively, are provided and master bladesshaped identical to the stator blades 29 are appropriately positionedbetween the mold rings. This assembly is then placed in a core box andthe sand is blown and the master blades are individually driven inwardlyor towards the axis of the sand core which is afterwards placed in thepattern.

A converter constructed as above provides performance comparable tothose having a generally circular toroidal circuit, but without thelatters disadvantage of requiring twisted blades. Such blades can onlybe made by the lost wax or Antioch plaster processes, or by the use ofcomplicated stamping or forming dies. All such variations are relativelyexpensive compared to the simply curved blades disclosed herein whichenable the use of draftable master blades in the preparation of the sandcores.

For optimum performance, the number of impeller blades 17 range from 20to 28 and their inlet and outlet angles range repectively from 33 to 56and from to -43 Where zero is defined as being axial in direction,positive is in the same direction as the normal forward rotation of theimpeller and negative indicates a direction opposite to the forwardrotation. Higher numbers of the impeller blades are related to the lowernegative angles, the lower the angle the higher will be the capacity orabsorbed torque.

For the turbine 19, the number of blades 22 range from 26 to 32 and theinlet and outlet angles range respectively from |l7.5 and +42, and from58 to 62. The smaller inlet angles of the turbine blades 22 are relatedto the smaller negative outlet angles of the impeller blades 17.

For the stator 26, the number of blades 29 range from 22 to 26,preferably 24 blades, whose inlet tangles range between 8 and and outletangles nange between +58 and +65".

Impeller having 28 to 43 outlet angles are preferably used with turbineshaving inlet angles ranging between +17.5 and while impellers havingoutlet angles of 0 to 20 are preferably used with turbines having inletangles between +38 and +42. Stators having inlet and outlet angles asstated above may be used with any of the mentioned impeller-turbinecombinations.

All of the inlet and outlet angles recited above for the several typesof blades are measured along the median design line 53, it being knownthat the angles at the torus walls 62 and 63 will be different from eachother and from the numerically given angles. For example, the inlet andoutlet angles of the impeller blades 17 at the wheel ring 12 are 5 to 9more and 0 to 2 less and the inlet and outlet angles of the blades 17 atthe core ring 16 are 4 to 8 less and 0 to 2 more, the inlet and outletangles of the turbine blades 22 at the wheel ring 20 are 3 to 5 more and2 to 4 more and the inlet and outlet angles of the blades 22 at the corering 21 are 3 to 5 less and 2 to 4 less, the inlet and outlet angles ofthe stator blades 29 at the wheel ring 27 are 4 to 6 less and 3 to 6more and the inlet and outlet angles of the blades 29 at the core ring28 are 4 to 6 more and 3 to 6 less than the inlet and outlet angles atthe median design line 53 for the impeller, turbine and stator blades17, 22 and 29, all respectively.

Further, for best results, the minimum, total flow areas between theblades of the impeller 15, turbine 19 and stator 26 must be related inthe following manner and respectively, 11% to 14%, 10.5% to 11%, and 9%to 9.5%, these areas being percentages of the area of a 1rR circle whereR is the outside radius of the torus 46.

FIGS. 6 and 7 are performance curves of the improved converter showing,respectively, input and stall torque 6 curves, and typical primarytorque and efficiency curves and are self-explanatory.

I claim:

1. An hydraulic torque converter having a generally pear-shaped torusprovided with a bladed outflow impeller, a bladed inflow turbine and asubstantially axial flow, bladed stator, the portion of the torusbetween the impeller outlet and turbine inlet being unbladed, the shapeof the torus being related by reference to an endless, pearshaped andconstruction, median design line which is bounded by a constructionrectangle whose shorter sides are parallel to. the axis of the converterand tangent to the outermost and innermost points of the design line atapproximate distances of .95R and .46R, respectively, from the converteraxis and whose longer sides are normal to the converter axis with aspacing of approximately 36R and tangent, respectively, to axiallyoutermost points of the design line wherein R is the outer radius of thetorus, the design line passing through a series of design points A to J,inclusive, determined by a system of X- and Y-coordinates beginning withthe radially outermost design point A of tangency of the rectangle withthe design line and proceeding in succession through the other designpoints in a direction opposite to that of the toroidal flow, thecoordinate system being related to the converter axis and a reference,construction base line perpendicular thereto and passing midway betweenthe longer sides of the rectangle as X- and Y-axes, respectively, thecoordinates having values for design point A of OR and .95R, for designpoint B of |.09R and 91R, for design point C of +.l8R and .63R, fordesign point D of +.17R and .56R, for design point B of +.10R and .48R,for design point F of OR and .46R, for design point G of .l2R and .50R,for design point H of .17R and .56R, for design point I of .18R and.63R, and for design point I of .09R and .91R, positive and negativevalues being measured in opposite directions, respectively, from thebase line, and the inner and outer walls of the torus being tangent toan infinite number of circles whose centers lie on the median designline with the diameter D of each circle being expressed as follows:

= (20% i 3%)1rR 21r distance of circle center from converter axis 2. Anhydraulic torque converter as defined in claim 1 wherein the curvatureof the median design line is further determined by a plurality ofconstruction lines each tangent to the median design line at one of thedesign points A to J, inclusive, respectively, and making angles withthe converter axis of 0, 49, 109, 152, 218, 247, 270 and 313.

3. An hydraulic torque converter as defined in claim 2 wherein theimpeller, turbine and stator blades are curved and devoid of twistbetween their inlet and outlet tips and the linear length of each bladeat the outer wall of the torus is greater than that at the inner wall,each blade having a casting taper from the outer to the inner wall ofthe torus.

4. An hydraulic torque converter as defined in claim 3 wherein thecross-sectional area of the torus normal to the median design line anddisregarding blade thickness is substantially constant and approximatelyequal to 20% of the area of a circle of radius R and wherein theminimum, total flow areas between the blades of the impeller, turbineand stator are respectively 11% to 14%, 10.5% to 11% and 9% to 9.5% ofthe area of a circle of R radius where R is the outer radius of thetorus.

5. An hydraulic torque converter as defined in claim 4 wherein thenumber of impeller, turbine and stator blades respectively range from 20to 28, 26 to 32 and 22 to 26, and the inlet and outlet angles for theimpeller, turbine and stator on the median design line respectivelyrange from 33 to 56 and 0 to 43, +17.5 to +42 and 58 to 62, and '8 to-l5 and +58 and +65 zero degree value being defined as axial indirection, and positive and negative degree values being defined,respectively, as in the same direction as and opposite to the normaldirection of impeller rotation.

6. An hydraulic torque converter as defined in claim 3 wherein the inletand outlet tips of the impeller, turbine and stator are position definedby design points and line intersections of the lateral surfaces ofassociated construction cones with a cross-sectional plane of the toruswhich includes the converter axis as follows: for each impeller blade,the lines determining positions of the inlet and outlet tips passthrough design points D and B and form with the converter axis angles of+3423 and -2725', for each turbine blade, the lines determiningpositions of the inlet and outlet tips pass through design points I andH and form with the converter axis angles of 2835 and 3453, for eachstator blade, the lines determining positions of the inlet and outlettips pass through design points G and E and form With the converter axisangles of,65 and-I-7638', all respectively, positive and negative anglevalues respectively indicating that the apexes of the associatedconstruction cones are located on the impeller and turbine sides of theconstruction base line.

No references cited.

1. AN HYDRAULIC TORQUE CONVERTER HAVING A GENERALLY PEAR-SHAPED TORUSPROVIDED WITH A BLADED OUTFLOW IMPELLER, A BLADED INFLOW TURBINE AND ASUBSTANTIALLY AXIAL FLOW, BLADED STATOR, THE PORTION OF THE TORUSBETWEEN THE IMPELLER OUTLET AND TURBINE INLET BEING UNBLADED, THE SHAPEOF THE TORUS BEING RELATED BY REFERENCE TO AN ENDLESS, PEARSHAPED ANDCONSTRUCTION, MEDIAN DESIGN LINE WHICH IS BOUNDED BY A CONSTRUCTIONRECTANGLE WHOSE SHORTER SIDES ARE PARALLEL TO THE AXIS OF THE CONVERTERAND TANGENT TO THE OUTERMOST AND INNERMOST POINTS OF THE DESIGN LINE ATAPPROXIMATE DISTANCES OF .95R AND .46R, RESPECTIVELY, FROM THE CONVERTERAXIS AND WHOSE LONGER SIDES ARE NORMAL TO THE CONVERTER AXIS WITH ASPACING OF APPROXIMATELY .36R AND TANGENT, RESPECTIVELY, TO AXIALLYOUTERMOST POINTS OF THE DESIGN LINE WHEREIN R IS THE OUTER RADIUS OF THETORUS, THE DESIGN LINE PASSING THROUGH A SERIES OF DESIGN POINTS A TO J,INCLUSIVE, DETERMINED BY A SYSTEM OF XAND Y-COORDINATES BEGINNING WITHTHE RADIALLY OUTERMOST DESIGN POINT A OF TANGENCY OF THE RECTANGLE WITHTHE DESIGN LINE AND PROCEEDING IN SUCCESSION THROUGH THE OTHER DESIGNPOINTS IN A DIRECTION OPPOSITE TO THAT OF THE TOROIDAL FLOW, THECOORDINATE SYSTEM BEING RELATED TO THE CONVERTER AXIS AND A REFERENCE,CONSTRUCTION BASE LINE PERPENDICULAR THERETO AND PASSING MIDWAY BETWEENTHE LONGER SIDES OF THE RECTANGLE AS X- AND Y-AXES, RESPECTIVELY, THECOORDINATES HAVING VALUES FOR DESIGN POINT A OF 0R AND .95R, FOR DESIGNPOINT B OF +.09R AND .91R, FOR DESIGN POINT C OF +. 18R AND .63R, FORDESIGN POINT D OF +.17R AND .56R, FOR DESIGN POINT E OF +10R AND .48R,FOR DESIGN POINT F OF 0R AND .46R, FOR DESIGN POINT G OF -.12R AND .50R,FOR DESIGN POINT H OF -.17R AND .56R, FOR DESIGN POINT I OF -.18R AND.63R, AND FOR DESIGN POINT J OF -.09R, AND .91R, POSITIVE AND NEGATIVEVALUES BEING MEASURED IN OPPOSITE DIRECTIONS, RESPECTIVELY, FROM THEBASE LINE, AND THE INNER AND OUTER WALLS OF THE TORUS BEING TANGENT TOAN INFINITE NUMBER OF CIRCLES WHOSE CENTERS LIE ON THE MEDIAN DESIGNLINE WITH THE DIAMETER D OF EACH CIRCLE BEING EXPRESSED AS FOLLOWS: